Method of making R-S (o) C NR1 R2 compounds

ABSTRACT

Intermediate compounds useful for manufacturing herbicidal active sulfoxide and sulfone compounds are described herein. The compounds have the following generic formula:  OR1  PARALLEL  R-S-C-N ANGLE R2   wherein R is selected from the group consisting of lower alkyl and haloalkyl; R1 and R2 taken together can form a heterocyclic ring structure having from 2 to 10 carbon atoms or alkyl substituted heterocyclic ring structure. The heterocyclic ring can be provided with cross-bonding.

This is a continuation of application Ser. No. 280,388, filed Aug. 14,1972, now abandoned.

DESCRIPTION OF THE INVENTION

This invention is directed to a novel group of compounds which may begenerally described as sulfoxide and sulfone derivatives ofthiocarbamates which are highly active herbicides. These compounds arerepresented by the generic formula: ##EQU2## wherein n is 1 or 2; R isselected from the group consisting of lower alkyl and haloalkyl; R₁ andR₂ taken together can form a heterocyclic ring structure having from 2to 10 carbon atoms or alkyl substituted heterocyclic ring structure. Theheterocyclic ring can be provided with cross-bonding.

The above-noted compounds can be prepared by reacting an oxidizing agentsuch as peracetic acid or m-chloroperoxybenzoic acid with athiocarbamate compound corresponding to the following formula: ##EQU3##wherein R, R₁ and R₂ have been defined above. The reaction is carriedout in the presence of a solvent such as chloroform, methylene chloride,benzene or toluene and at a reduced temperature of from about -25°C. toabout 60°C. The amount of oxidizing agent used must be at least onemolar equivalent to form the sulfoxide derivative and at least two molarequivalents to form the sulfone derivatives.

The thiocarbamate compounds are known herbicides and their method ofsynthesis is known; see U.S. Pat. Nos. 2,913,327, 2,983,747, 3,133,947,3,175,897 and 3,185,720 for example. However, the use of thesethiocarbamates as reactive intermediates to form other compounds thatalso have pesticidal activity is unexpected.

In order to illustrate the merits of the present invention the followingexamples are provided:

Example I ##EQU4##

A solution was formed containing 11.2 grams (0.055 mole) ofm-chloroperoxybenzoic acid and 200 cc. of methylene chloride in areaction vessel. This solution was cooled in dry ice to -14°C. wherein9.4 grams (0.05 mole) of S-ethylhexahydro-1H-azepine-1-carbothioate wasadded over a period of 4 minutes wherein the temperature increased to-13°C. The reaction mass was cooled to -14.5°C. and allowed to fluctuatefor about 1 hour wherein the reaction mass was cooled to -5°C. Whereinthe reaction mass was allowed to warm to 20°C. The reaction mass wasthen cooled to 2.5°C. wherein the mixture was filtered and the cake waswashed with two portions of 25 cc. of methylene chloride. The combinedfiltrate was washed with four portions of 100 cc. 5 percent sodiumcarbonate solution and two portions of 100 cc. of water, dried overmagnesium sulfate and concentrated in the rotary evaporator, first underwater pump vacuum and finally under high vacuum to yield 9.1 grams ofresidual liquid. This residual liquid was redistilled to yield 8.0 gramsof product, n_(D) ³⁰ -- 1.5274.

Example II ##EQU5##

A solution was formed containing 22.3 grams (0.11 mole) ofm-chloroperoxybenzoic acid in 300 cc. of methylene chloride in areaction vessel. This solution was warmed to 29.5°C. wherein 9.4 gramsof S-ethylhexahydro-1H-azepine-1-carbothioate was added over a period ofthree minutes. During the addition the temperature rose to 41°C. After1.5 hours the solution was cooled to 9°C. and was filtered with the cakebeing washed with two portions of 25 cc. of methylene chloride. Thefiltrate was washed with four portions of 100 cc. 5% solution of sodiumcarbonate and two portions of 100 cc. of water, dried over magnesiumsulfate and concentrated in a rotary evaporator under water pump vacuumto yield 10.3 grams of product, n_(D) ³⁰ -- 1.5000.

Example III ##EQU6##

A solution was formed containing 22.3 grams (0.11 mole) ofm-chloroperoxybenzoic acid in 300 cc. methylene chloride. This solutionwas cooled to 30.5°C. wherein 11.5 grams (0.05 mole) ofS-isopropyl-5-ethyl-2-methylpiperidine-1-carbothioate was added over aperiod of 3 minutes. During the addition the temperature rose to 41.5°C.The reaction was maintained at this temperature and then cooled in iceand filtered with the cake being washed with two portions of 25 cc. ofmethylene chloride and dried in the oven. The combined filtrate waswashed with four portions of 100 cc. 5% solution sodium carbonate andtwo portions of 100 cc. water, dried over magnesium sulfate andconcentrated in the rotary evaporator, first under water pump vacuum andfinally under high vacuum to yield 12.2 grams of product, n_(D) ³⁰ --1.4871.

Example IV ##EQU7##

A solution was formed containing 12.8 grams of S-butyldecahydroquinoline-1-carbothioate (0.05 mole) in 200 cc. of methylenechloride. This solution was cooled to -14°C. wherein 10.7 grams (0.0525mole) of m-chloroperoxybenzoic acid was added over a period of 5minutes. The reaction mass was maintained at this temperature for aperiod of about 1 hour and 10 minutes, wherein it was warmed to -5°C.and maintained at this temperature for another 30 minutes. Thereafter,the reaction mass was allowed to warm to 16°C. wherein the mixture wasfiltered and the cake washed with two portions of 25 cc. of methylenechloride. The combined filtrate was washed with four portions of 100 cc.5% sodium carbonate solution and two portions of 100 cc. water, driedover magnesium sulfate and concentrated in a rotary evaporator, firstunder water pump vacuum and finally under high vacuum to yield 12.0grams of product, n_(D) ³⁰ -- 1.5282.

Other compounds were prepared in an analogous manner starting with theappropriate starting materials as outlined above. The following is atable of compounds representative of those embodied by the presentinvention. Compound numbers have been assigned to them and are used foridentification throughout the balance of the specification.

                  TABLE I                                                         ______________________________________                                                 OR.sub.1                                                                      ∥                                                                    R--S(O).sub.n --C--N∠                                                   R.sub.2                                                              Compound                                                                      Number      R        R.sub.1 and R.sub.2                                                                           n                                        ______________________________________                                                             CH.sub.2 --CH.sub.2 --CH.sub.2                           1          --C.sub.2 H.sub.5                                                                       ∠|                                                                             1                                                             CH.sub.2 --CH.sub.2 --CH.sub.2                                                CH.sub.2 --CH.sub.2 --CH.sub.2                           2          --C.sub.2 H.sub.5                                                                       ∠|                                                                             2                                                             CH.sub.2 --CH.sub.2 --CH.sub.2                                                CH.sub.2 --CH.sub.2                                      3          n--C.sub.3 H.sub.7                                                                      ∠∠CH.sub.2                                                                        1                                                             CH.sub.2 --CH.sub.2                                                           CH.sub.2 --CH.sub.2                                      4          n--C.sub.3 H.sub.7                                                                      ∠∠CH.sub.2                                                                        2                                                             CH.sub.2 --CH.sub.2                                                           C.sub.2 H.sub.5                                                               |                                                                    CH.sub.2 --CH                                            5          i--C.sub.3 H.sub.7                                                                      ∠∠ CH.sub.2                                                                       1                                                             CH--CH.sub.2                                                                  |                                                                    CH.sub.3                                                                      C.sub.2 H.sub.5                                                               |                                                                    CH.sub.2 --CH                                            6          i--C.sub.3 H.sub.7                                                                      ∠∠CH.sub.2                                                                        2                                                             CH--CH.sub.2                                                                  |                                                                    CH.sub.3                                                                      CH.sub.3                                                                      |                                                                    CH.sub.2 --CH                                            7          --C.sub.3 H.sub.6 --Cl                                                                  ∠∠CH.sub.2                                                                        1                                                             CH--CH.sub.2                                                                  |                                                                    CH.sub.3                                                                      CH.sub.3                                                                      |                                                                    CH.sub.2 --CH                                            8          --C.sub.3 H.sub.6 --Cl                                                                  ∠∠CH.sub.2                                                                        2                                                             CH--CH.sub.2                                                                  |                                                                    CH.sub.3                                                                      CH.sub.2 --CH.sub.2                                      9          n--C.sub.4 H.sub.9                                                                      CH.sub.2 ∠∠CH.sub.2                                                               1                                                             CH--CH                                                                        ∠∠CH.sub.2                                                        CH.sub.2 -- CH.sub.2                                 

Herbicidal Screening Tests

As previously mentioned, the novel compounds herein described arephytotoxic compounds which are useful and valuable in controllingvarious plants species. Compounds of this invention are tested asherbicides in the following manner.

A. Preemergence Herbicide Screening Test

Using an analytical balance, 20 mg of the compound to be tested isweighed out on a piece of glassine weighing paper. The paper andcompound are placed in a 30 ml wide-mouth bottle and 3 ml of acetonecontaining 1% Tween 20 is added to dissolve the compound. If thematerial is not soluble in acetone, another solvent such as water,alcohol or dimethylformamide (DMF) is used instead. When DMF is used,only 0.5 ml or less is used to dissolve the compound and then anothersolvent is used to make the volume up to 3 ml. The 3 ml of solution issprayed uniformly on the soil contained in a small Styrofoam flat 1 dayafter planting weed seeds in the flat of soil. A No. 152 DeVilbissatomizer is used to apply the spray using compressed air at a pressureof 5 lb./sq.in. The rate of application is 8 lb/acre and the sprayvolume is 143 gal/acre.

On the day preceding treatment, the Styrofoam flat which is 7 incheslong, 5 inches wide and 2.75 inches deep in filled to a depth of 2inches with loamy sand soil. Seeds of seven different weed species areplanted in individual rows using one species per row across the width ofthe flat. The seeds are covered with soil so that they are planted at adepth of 0.5 inch. The seeds used are hairy crabgrass (Digitariasanguinalis), yellow foxtail (Setaria glauca), water grass (Echinochloacrusgalli), red oat (Avena sativa), redroot pigweed (Amaranthusretroflexus), Indian mustard (Brassica juncea) and curly dock (Rumexcrispus). Ample seeds are planted to give about 20 to 50 seedlings perrow after emergence depending on the size of the plants.

After treatment, the flats are placed in the greenhouse at a temperatureof 70° to 85°F and watered by sprinkling. Two weeks after treatment thedegree of injury or control is determined by comparison with untreatedcheck plants of the same age. The injury rating from 0 to 100% isrecorded for each species as percent control with 0% representing noinjury and 100% representing complete kill.

B. Postemergence Herbicide Screening Test

Seeds of six plant species, including hairy crabgrass, watergrass, redoat, mustard, curly dock and Pinto beans (Phaseolus vulgaris) areplanted in the Styrofoam flats as described above for preemergencescreening. The flats are placed in the greenhouse at 70° to 85°F andwatered daily with a sprinkler. About 10 to 14 days after planting whenthe primary leaves of the bean plants are almost fully expanded and thefirst trifoliate leaves are just starting to form, the plants aresprayed. The spray is prepared by weighing out 20 mg of the testcompound, dissolving it in 5 ml of acetone containing 1% Tween 20 andthen adding 5 ml of water. The solution is sprayed on the foliage usinga No. 152 DeVilbiss atomizer at an air pressure of 5 lb/sq.in. The sprayconcentration is 0.2% and the rate is 8 lb/acre. The spray volume is 476gal/acre.

The results of these tests are shown in Table II.

                  TABLE II                                                        ______________________________________                                        HERBICIDAL ACTIVITY - SCREENING RESULTS                                       Compound   Percent Control* at 8 lb/A                                         Number     Preemergence   Postemergence                                       ______________________________________                                        1          91             65                                                  2          0              26                                                  3          91             68                                                  4          0              69                                                  5          99.9           77                                                  6          0              65                                                  7          99.7           74                                                  8          0              67                                                  9          99.7           83                                                   *Average for seven plant species in the preemergence test and for six         plant species in the postemergence test.                                 

    Compound   Percent Control* at                                                Number     20 lb/A Preemergence                                               ______________________________________                                        2          12                                                                 ______________________________________                                         *Average for seven species.                                              

What is claimed is:
 1. A process of manufacturing a pesticidal activecompound corresponding to the following formula: ##EQU8## wherein n is 1or 2; R is selected from the group consisting of lower alkyl and lowerhaloalkyl; R₁ and R₂ taken together form an alkylene group having 2 to10 carbon atoms, said alkylene group being unsubstituted or substitutedwith alkyl groups having 1- 2 carbon atoms, or R₁ and R₂ taken togetherform ##EQU9## comprising the steps of: a. combining an oxidizing agentselected from peracetic acid and m-chloroperoxybenzoic acid and athiocarbamate compound in a solvent system; said thiocarbamate havingthe following formula: ##EQU10## b. maintaining the temperature between-25°C. and 60°C.; c. said oxidizing agent being present in an amount ofat least one stoichiometric equivalent and not more than twostoichiometric equivalents.
 2. The process as set forth in claim 1wherein said oxidizing agent is m-chloroperoxybenzoic acid.